July 2012

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Controls Specification Development

What is the right approach?

Paul Ehrlich, Ira Goldschmidt & Angela Lewis
Building Intelligence Group

As published
Engineered Systems 
July Issue - Column

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In past columns we have talked about the elements of a good controls specification.  As a re-cap a good controls specification includes the following parts:

•    Specification:  Typically appears in section 230900 or 230923.  This includes three sections; 1) General - which describes the system, interaction with other specification sections, and submittal requirements. 2) Product – which describes the required hardware and software.  3) Execution - which talks about workmanship and installation requirements. 
•    Sequence of Operations:  The sequence is probably the most important part of the controls design.  Sequences describe in a text-based format how each system should be operated.
•    Points (or object) list:  The points list shows the required hardware and software points that are to be provided.  Often the point list also describes which points are scheduled, alarmed and trended as well.  Note that the sequence of operations and points list can be shown on project drawings, in the execution section of the specification, or in section 230933.

It is not at all unusual to see projects that include significantly less detailed controls designs.  One reason given for this is that controls are viewed as “design build” and the designer has left the design details of the controls system up to the contractor.  For simple systems this may be a valid option, but it is not recommended for larger, more complex systems.

We are also seeing projects were the designer has decided to include significantly more detail.  Examples of this include control logic diagrams (shown as flow charts) on project drawings.  On the more extreme end some projects include full controls engineering as part of the project engineering including drawings showing point-to-point wiring and panel layouts (the type of detail that would normally be found only in the controls submittals).  This typically occurs when the owner is adding to an existing control system and may be doing some of the programming with their in-house staff.

What is the right approach?  It really depends on the project and the owner’s needs.  We tend to favor a fairly detailed design with careful attention to specifying an open system that works with what the owner may already have installed (without going to the extreme of showing submittal level wiring/panel details).  Our designs typically have detailed sequences and points lists to help owners get the most out of their systems.  You can make a good argument that for a simple, largely unitary solution that less detail may be adequate.  After all unitary systems typically come with factory installed controllers that have fairly limited flexibility.  Providing more details can also be valuable in special cases, but does not necessarily replace the detail that is provided in a controls submittal and as built diagrams including portable documents which include schematics, sequences, valve and damper schedules, and wiring details.

About the Authors

Paul and IraPaul and Ira first worked together on a series of ASHRAE projects including the BACnet committee and Guideline 13 – Specifying DDC Controls. The formation of Building Intelligence Group provided them the ability to work together professionally providing assistance to owners with the planning, design and development of Intelligent Building Systems. Building Intelligence Group provides services for clients worldwide including leading Universities, Corporations, and Developers. More information can be found at www.buildingintelligencegroup.com  We also invite you to contact us directly at Paul@buildingintelligencegroup.com or ira@buildingintelligencegroup.com


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